The present invention relates to an improved device for forming a web consisting of parallel spaced threads, extending transversely relative to the length of the web.
In the description which follows, such a web will be referred to by the expression "weft web" and the threads constituting the web will be referred to by the expression "weft threads".
Very many devices are currently used for producing weft webs which are intended to be combined with longitudinal parallel threads, the cohesion of the whole being provided, for example, by gluing so as to form articles usually referred to by the expression "non-woven textile nets". These weft webs can optionally also be used as they are, for example as a non-woven reinforcing element for paper, or even as an element employed in the manufacture of knitted articles produced by the so-called "frontal weft insertion" technique, which consists of incorporating, over the entire length of the knitting machine or Raschel machine, a weft thread into each row of stitches or in accordance with a defined frequency.
A well-known technique for producing such weft webs, which is described in particular in French Pat. Nos. 1,335,418, 1,367,567 and 1,537,811, consists, in general terms, of distributing a plurality of weft threads around pegs arranged on two endless belts which are separated from one another by a distance corresponding to the width of the web which it is desired to produce. According to this technique, the element which dispenses the weft thread is located above the two endless belts carrying the pegs and consists of a revolving unit which, in the course of its rotation, places the threads between, and around, the said pegs.
Such a device is complex, especially because it requires special guide members for positioning the weft threads around the pegs, if it is desired to obtain webs consisting of threads which are strictly parallel to one another. Furthermore, it is rather awkward to ensure that the weft threads are held around the pegs, as the threads can easily slip off the pegs.
Another, very old technique which is mentioned in the abovementioned patents for the production of articles of the non-woven net type consists in causing the longitudinal threads to advance intermittently and dispensing the transverse threads during the pause periods, the transverse threads thus being selected at the edges of the strip. In this technique, the same problem as previously arises, namely how to hold the ends of the transverse threads or weft threads.